Center-finder.



J. B. GIERN 6: A. P. ANHOLTT.

CENTER FINDER.

APPLICATION FILED JUNE 1. 1917.

31.,%8.6. Patented Jan. 15, 1918.

2 SHEETS-SHEET I.

J. B. GIERN & A. P. ANHOLTT. CENTER FINDER.

APPLICATION man JUNE], 1917.

1 Patenizari Jan. 15 2 swans-4H5 2.

@AEB

JAMES B. GIERN AND ANDERS P. ANI-IOLT'JI, OF DETROIT, MICHIGAN.

CENTER-FINDER.

Specification of Letters Patent.

Patented Jan. T5, TWLB.

Application filed June 1, 1917. Serial No. 172,200.

To all whom it may concern:

Be it known that we, JAMES B. GIERN and Answers P. ANHoL'rr, subjects of theKing of Denmark, and residents of Detroit, county of Wayne, and State of Michigan, have invented certain new and useful Improvements in Center-Finders, of which the following is a specification.

Thi invention relates to new and useful improvements in center finders or toolmakers buttons for machine and tool work, and is an improvement in thetoolmakers buttons now known to the trade.

As is well known to those skilled in the art, these buttons consist of hardened steel cylinders supported by screws passing loosely through their centers, and are ar ranged to be locked in different positions of adjustment by friction washers under the screw-heads bearing against the ends of the cylinders.

In tool and die work these buttons must be set with extreme accuracy. They must be located within the fraction of one one-thousandth of an inch. It is a slow and expensive operation to set them, for the reason that after an adjustment has been made the screws must be tightened to hold them, and in turning the screws the friction of the washer tends to shift the button.

With the present invention the button or center finder is held on a stem by means which permits of the button being positioned or centered on the stem by the opera tor, and then another means is provided for rigidly locking the button to the stem with out displacing the button from the position it has been set.

The invention consists of certain novel features of construction and combinations of parts which will be hereinafter described and pointed out in the claims.

In the accompanying drawings Figure 1 is a view in perspective of a heavy duty drill press, illustrating a type of machine which may be employed, and showing the invention applied thereto;

Fig. 2 is a longitudinal sectional view of the invention;

Fig. 3 is a vertical sectional view of the retaining cap;

Fig. 4 is a plan view showing the interior of the cap;

rug. 5 is a perspective view of the locking cap; and

. Fig. 6 is a perspective view of the button.

{is shown in the drawings, A is a cylindrical stem or member formed of steel or other suitable material and having its surface ground true so as to be held in the splndle of a milling machine or lathe. The enlarged end of this member is formed with two diameters 1 and 2, both of which are threaded, and the end face '3 is a ground surface exactly perpendicular to the axis of the cylinder A.

B, is the cylindrical button member, preferably formed of hardened steel, having one flanged end 4 with its outer face ground exactly perpendicular to its axis and arranged to abut the end face 3 of the member A. It will be noted that so long as the sur faces 3 and at are in contact the button B must be parallel with the member A, and the button B and member A, if not concentric, must be eccentric with their axis parallel.

The free end of the button B is provided with a ground center 5 for use in centering, as will be readily understood by those skilled in the art.

The smaller diameter portion 2 of the stem A, has a retaining cap or shell screwed thereon. The cap is provided with a central opening 7 through which the button B extends, the inner end of the button being reduced as at 7 to permit of its being shifted laterally on the face 3 of the stem A for positioning the button on the stem. Recesses 8 are formed in the end of the cap 6, and on the inner face thereof, for the reception of coiled springs 9. Balls 10 are interposed between the springs and inner face of the flange 4 of the button B, for forming ayielding engagement between the cap and button so that the button may be easily positioned or centered on the stem.

A. plurality of holes 11 are formed in the end of the cap 6 through which extend pins 12, the pins being adapted to engage the inner face of the flange 4 of the button B.

A locking cap or shell 18 has threaded engagement with the larger diameter portion 1, of the stem A, and is knurled as shown at 14, for hand operation to shift its position on the thread. The cap 13 is provided with an opening 15 in the end thereof to allow for the passage and relative movement of the button B. The cap is adapted to be screwed onto the stem A, after the button B has been adjusted with respect to the stern A, and" the end of the cap 113 will eome in contact with the projecting ends of the pins 12, causing the pins to be forced through the cap 6 and engage the flange 4t of the button B, for locking the button against movement, and holding it frictionally in contact with the face 3 of the stem.

In Fig. 1 a heavy duty drill press is shown, which is one of many types of ma chines with which this invention may be employed, and for the purpose of illustratingthe use of the button, the following operation is set forth, but it is not the lntention to limit the use of the invention to this particular machine.

When it is desired to make patterns or special tools, and in this instance, a tool for drilling bolt holes in the end of a gasolene engine crank case, a block of steel. or cast iron C, is placed on the bed of the drill press D. It will be assumed that the bolt holes have already been laid out around the large. hole a, which is the end hole in the crank case. It is now necessary to drill the holes designated bcd. The blueprint covering the crank case prepared by the engineering department shows that the hole marked 0 carries the bearing for the cam shaft, and the holes 6 and (Z are bolt holes over this bearing. The crank shaft naturally runs through the center of the large hole a in the end of the crank case, and the cam shaft running through the hole marked 0, which hole 0 must be an absolutely correct distance from the center of the crank shaft as well as from the base line, which i generallywthe upper surface of the crank case. on which the cylinders rest. In making theitool, or tool plate as it will be termed, theedge of the block of. iron, from whichcthetool plate is made, is taken as its base line, andit is exactly machined to a true surface on every side.

The. bolt holes around the hole a having been laid: out, two buttons 6 and f,.of standard articles of commerce, are inserted in two of'the holes, and as the operator knows the; distance between the holes, in which the buttons re and f are inserted, and the holec,

which "is to be formed for the cam shaft, it

is necessary for him to drill the hole 0, at the-proper point.

Theistem A, is inserted in the spindle of thedrillpress D, and the button B, being held; inyielding engagement with the surface of. the stem A, can be positioned thereon, by. the operator placing his finger,

or. an lnstrument, against the button as it and-the-spindlev is rotated. When the button :hasbeen centered or positioned on the stem,the locking cap 13 is screwed ontothe stein, forcing thepins 12 againstthe inner faceof-the flange A of the buttonB, locking the buttonlto the stem A. It will be noted that as the cap 6 isiheld rigid in relation-totheizstem A, and. holdsthe pins: .12. in

positions fixed from transverse movement relative to the stem A, the operation of tightening the cap 13 cannot shift the position of the button B while locking it to customary practice with machinists, the spindle is lowered and the button B, brought into the same horizontal plane with the buttons c and f, that is, the free end of the button B, nearly touches the surface of the tool plate C. lVith his micrometer the operator measures the distance from the surface of button B to the base line or edge of the tool plate 0, and also measures the distance from the surface of the button B to the surfaces of the buttons 6 and f, respectively. Knowing the exact diameter of the buttons to a positive degree, the operator can by lifting the spindle and button B, exactly center as regards the point on the plate where the hole 0 is to be drilled.

The tool plates must be laid out with extreme accuracy, and as is wellknown, an object or button must be employed whichis of dimensions known to the operator and having surfaces from which an accurate measurement can be made, as the tool platesmust be laid out with an exactness which allows a variation from the dimensions given on the blueprint of one-half of onethousandth of an inch, and in some casesas close as one-fourth of one-thousandthof an inch.

Toolmakers buttons of the old type, as well as their use in different operations, such as locating the center of'a milling machinespindle, are well known in the art, and a description of their function is unnecessary. Our improved type of button or. indicator is used for the same purpose and inthe-same way,-anda more detailed description of its use than as set forth is thought unnecessary." The great advantage in the present device lies in the fact, that the locking meansconsisting of the pins 12 and the cap 13 cannot possibly change the position ofathe: button Bwhen operated to lock the button in any desired position.

We claim:

1. In a toolmakers button,wthe combina-' tion of a stem and a button, means for holtling the button in contact with the stem,:and means for exerting pressure on the button for looking it to the stem without displacing the button.

2. In a toolmakers button, the combination of a stem and a button, means for hold-1 ing the button in contact'with the stem in a yielding manner, and means for exerting tion of a stem and a button, means for.

looselyiholding" the button-win contact with nasaeeo the stem, means carried by said means and engaging the button, and means for operating said engaging means for locking the button against movement.

l. In a center finder, the combination With relatively movable cylindrical members, of yielding means for holding said members parallel While permitting relative lateral adjustment, and means for locking said members in different positions of adjustment.

5. In a center finder, the combination With two cylindrical members having their end surfaces parallel and abutting, of a retaining cap carried by one of said members and carrying vyielding means for holding said other member in abutment, and an adjust able cap carried by said first mentioned member, and locking means for the members operated by said adjustable cap.

6. In a tool-makers button, the combination with a stem adapted for insertion in the spindle of a machine, of a button, means for yieldingly holding the end of said button in contact with the end of said stem, While per niiitting lateral relative adjustment between the stem and button, and locking means independent of said yielding means for connecting the stem and button together.

JAMES B. GIERN. ANDERS P. ANHOLTT.

Eunice of this patent may be obtained for five cents each, by addressing the fiommissioner at Patents.

Waslflngton, JD. W 

